Question
I took ur advice & put rubbing alcohol in the soil of my house plants which had many nats. The alcohol killed the purple passion and it seems that its slowly killing the defenbaccia.  What happened? you did not specify pour or spray...of course i poured the alcohol.  

Answer
Mary,

You are still overwatering the plants. Alcohol in the soil will only help if you stop overwatering the plants. When you water a plant you need to empty the drain tray of all excess water & alcohol an hour after you water it then you do not water the plant again until the plant is dry. That means until the soil feels dry on the surface and if you insert a bamboo skewer into the soil it comes out dry. Also the plant feels light weight when it is picked up.

Plants roots need alternating periods of moist then dry. During the dry periods they breathe in carbon dioxide through the soil and expel oxygen through the leaves. If the soil is constantly moist they cannot go through this cycle so the roots start to rot and the rotting roots attract fungus gnats which then lay eggs in the soil. The only way to get rid of them quickly is the alcohol in the soil will kill the gnaqts and eggs and will nt hurt the plants roots but if you do not let the plants dry out you just continue the root rot and kill the plant that way. You have to let your plants dry out between waterings. You should only need to use the alcohol 1 time. The gnats should not come back if you empty the drain tray an hour after watering the plant and let the plant dry out between each watering. Good luck.

Darlene